Fast zooms and primes get the glory, but they’re not always the most practical choices. If you’re a full frame (α7-series) shooter and you want to travel light without sacrificing range or cropping down to an APS-C format, there are 3 full-frame variable aperture zooms that you should consider, the 70-300 f4.5-5.6 G OSS, 28-70mm F3.5-5.6 OSS and 24-240mm f/3.5-6.3 OSS.
Zoom range. Between these three lenses you get a 10X, a 4.3X and a 2.5X. The 24-240mm has been called one of the best travel lenses available because of its massive, do it all range. In shooting situations where you don’t know what to expect, like travel, being able to have a single lens on a single body and cover true wide-angle to a 240mm telephoto is a huge advantage. The 28-70 is an ideal range for street shooters and as a walk-around lens. The 70-300 is a true telezoom for everything from portraits to action and wildlife. And, couple a 28-70 and a 70-300 and you get 28mm wide to 300mm telephoto in just 2 lenses.
Size & weight: A fast zoom can be awesome but part pf the tradeoff is weight. The Sony 28-70 weighs just 10.5 ounces! The 24-240 is 27.6 ounces and the 70-300 comes in at 30.2 ounces. Constant aperture models with a similar range can weigh 3 times as much. That tradeoff can make the difference between keeping the lens with you and leaving it at home because you don’t feel like carrying the weight around.
Cost: Generally-speaking, it’s easier to make a variable-aperture zoom. The design can be simpler with fewer elements (hence the size and weight differences) and there’s a significant cost savings. The 24-240 can be purchased for about $999). The 70-300 comes at $1199. The 28-70 is available for $499.
Here are some reviews:
70-300 f4.5-5.6 G OSS
“In terms of optical quality alone, the FE 70-300mm F4.5-5.6 G OSS is on par with the best of its rivals. It has good sharpness at the longer focal lengths, though closing down a stop at 300mm to f/8, when light levels permit, improves levels significantly. While that is a limitation of models like this, this has to be balanced with the extra versatility that they offer over a fixed-focal length 300mm lens. While Sony users still don’t have much choice for longer focal length lenses like this, this model is nonetheless a welcome and attractive addition to the lineup.” -DxOMark
“I’d actually even consider [the 70-300mm] to be one of the best bang for your buck lenses that Sony offers. You get weather resistance, great image quality, decent autofocus, and a compact size for a little over $1,000” -ThePhoblographer
“As a landscape photographer, I’m still very excited for the existence of this lens. I want my images sharp, and I want them sharp everywhere; this lens gets me there.
“Being sharp also means being in focus, and the 70-300mm was a good performer in this area. Photographing small fidgety birds in low light can be one of the most autofocus intensive subjects to work with, and I got just the chance while shooting with this lens. When you are more worried about whether you can freeze a bird with your shutter speed and ISO as the sun is touching the horizon rather than if you can get there in time with focusing, it’s a good sign.” -Fstoppers
“I found [the 70-300] to offer great build, feel, nice balance on an α7R II and the image quality was and is beautiful. No softness or focus issues from what I have seen. I feel this will be a very attractive lens to those looking for something in this focal length range, and it sure beats the hell out of my old Canon 70-300 DO.” -SteveHuffPhoto
“The optics provide high contrast and clarity, with great definition of fine detail. At maximum aperture, the central 70% of the frame is very sharp; stopping down to f/8 provides excellent sharpness across the entire frame. Even in strong side lighting at sunset on Pier 39, the long lens hood and multi-layer coatings effectively prevented flare. While this was only a brief hands-on trial of the new lens, I was impressed with the very fine performance; my best images are suitable for making poster-size prints.” -PhotoNews
28-70mm F3.5-5.6 OSS
“The Sony FE 28-70mm F3.5-5.6 OSS is a very competent, if unspectacular, standard zoom lens for the Sony α7R/α7 full-frame compact system cameras. It delivers excellent sharpness in the centre of the frame almost throughout its aperture range…” -PhotographyBlog
“Indeed, there is very little to complain about with this lens and if you’re using it for general shooting purposes, then you’ll be very satisfied.” The review continues, “[Y]ou’d be hard pressed to really hate on this lens for its sharpness overall in the spectrum of photography. Canon and Nikon have nothing that can touch this.” And, “The Sony 28-70mm f/3.5-5.6 OSS is a lens that will acceptably suit the needs of a shooter who craves overall versatility from a mirrorless camera with a full frame sensor.” -ThePhoblographer
24-240mm f/3.5-6.3 OSS
And, “Build quality is excellent.” And, “Image stabilization combined with the in-camera stabilization of the α7 II is superb, perhaps the best I have used.” -SteveHuffPhoto
"[T]he image quality delivered by the FE 24-240mm is good for a superzoom, and as we’ve seen in the Sony FE 24-240mm vs Nikon 28-300mm analysis, the Sony is as good in most areas and actually slightly better than the Nikon at the wider apertures. The FE 24-240mm’s performance is also better at the wider focal lengths between 24-50mm." And, "So if you’re looking for a good quality standard zoom with the added versatility of being able to shoot telephoto without changing lenses, the FE 24-240mm is a convenient and good value choice for Sony α7 shooters." -DxOMark
“This new 24-240mm is a full-frame-compatible lens that offers an impressive 10x zoom range, giving full-frame α7-series camera users the ability to forgo changing lenses in situations where they may not have time to or just don’t feel like it.”“The 24-240mm offers an extremely versatile range from wide to telephoto while still being relatively compact at the wide end.” –B&H Photo Explora Blog
“Considering the cost and limited range of the current Sony Zeiss and G lens zooms, the SEL24240 is a good option in my opinion for those looking for an all-in-one solution. Perfect for a photo walk or hike without the gear bag, or for vacation where bringing more than one lens is not always practical.
“I really enjoyed using the lens and something like this would be perfect for my current personal life as far as family photos and capturing the moments that matter. Soccer games, birthday parties, and other family gatherings are mostly what goes on, and this lens is a great option for almost all activities.” -SonyAlphaLab